__tdx_hypercall() doesn't work for a TDX guest running on Hyper-V,
because Hyper-V uses a different calling convention, so add the
new function __tdx_ms_hv_hypercall().
Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
---
arch/x86/coco/tdx/tdcall.S | 87 +++++++++++++++++++++++++++++++++
arch/x86/include/asm/mshyperv.h | 2 +
2 files changed, 89 insertions(+)
diff --git a/arch/x86/coco/tdx/tdcall.S b/arch/x86/coco/tdx/tdcall.S
index f9eb1134f22d..468b71738485 100644
--- a/arch/x86/coco/tdx/tdcall.S
+++ b/arch/x86/coco/tdx/tdcall.S
@@ -13,6 +13,8 @@
/*
* Bitmasks of exposed registers (with VMM).
*/
+#define TDX_RDX BIT(2)
+#define TDX_R8 BIT(8)
#define TDX_R10 BIT(10)
#define TDX_R11 BIT(11)
#define TDX_R12 BIT(12)
@@ -203,3 +205,88 @@ SYM_FUNC_START(__tdx_hypercall)
REACHABLE
jmp .Lpanic
SYM_FUNC_END(__tdx_hypercall)
+
+/*
+ * __tdx_ms_hv_hypercall() - Make hypercalls to Hype-V using TDVMCALL leaf
+ * of TDCALL instruction
+ *
+ * Transforms values in function call arguments "input control, output_addr,
+ * and input_addr" into the TDCALL register ABI. After TDCALL operation,
+ * Hyper-V has changed the memory pointed by output_addr, and R11 is the
+ * output control code. Note: before the TDCALL operation, the guest must
+ * share the memory pointed by input_addr and output_addr with Hyper-V.
+ *-------------------------------------------------------------------------
+ * TD VMCALL ABI on Hyper-V:
+ *-------------------------------------------------------------------------
+ *
+ * Input Registers:
+ *
+ * RAX - TDCALL instruction leaf number (0 - TDG.VP.VMCALL)
+ * RCX - BITMAP which controls which part of TD Guest GPR
+ * is passed as-is to the VMM and back.
+ * R10 - Set to Hyper-V hypercall input control code.
+ * Note: legal Hyper-V hypercall input control codes
+ * are always non-zero, i.e. they don't conflict with
+ * TDX_HYPERCALL_STANDARD.
+ * R8 - Output physical addr.
+ * RDX - Input physical addr.
+ *
+ * Output Registers:
+ *
+ * RAX - TDCALL instruction status (Not related to hypercall
+ * output).
+ * R11 - Output control code.
+ *
+ *-------------------------------------------------------------------------
+ *
+ * __tdx_ms_hv_hypercall() function ABI:
+ *
+ * @arg (RDI) - Input control code, moved to R10
+ * @arg (RSI) - Output address, moved to R8
+ * @arg (RDX) - Input address. RDX is passed to Hyper-V as-is.
+ *
+ * On successful completion, return the hypercall output control code.
+ */
+SYM_FUNC_START(__tdx_ms_hv_hypercall)
+ FRAME_BEGIN
+
+ /* Set TDCALL leaf ID (TDVMCALL (0)) in RAX */
+ xor %eax, %eax
+
+ /* Do not leak the value of the output-only register to Hyper-V */
+ xor %r11, %r11
+
+ /* Load input control code */
+ mov %rdi, %r10
+
+ /* Load output addr. NB: input addr is already in RDX. */
+ mov %rsi, %r8
+
+ /* Expose these registers to Hyper-V as-is */
+ mov $(TDX_RDX | TDX_R8 | TDX_R10 |TDX_R11), %ecx
+
+ tdcall
+
+ /*
+ * RAX==0 indicates a failure of the TDVMCALL mechanism itself and that
+ * something has gone horribly wrong with the TDX module.
+ *
+ * The return status of the hypercall operation is in a separate
+ * register (in R11). Hypercall errors are a part of normal operation
+ * and are handled by callers.
+ */
+ testq %rax, %rax
+ jne .Lpanic_ms_hv
+
+ /* Copy output control code as the function's return value */
+ movq %r11, %rax
+
+ FRAME_END
+
+ RET
+.Lpanic_ms_hv:
+ call __tdx_hypercall_failed
+ /* __tdx_hypercall_failed never returns */
+ REACHABLE
+ jmp .Lpanic_ms_hv
+SYM_FUNC_END(__tdx_ms_hv_hypercall)
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 61f0c206bff0..fc09b6739922 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -36,6 +36,8 @@ int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages);
int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id);
int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flags);
+u64 __tdx_ms_hv_hypercall(u64 control, u64 output_addr, u64 input_addr);
+
static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
{
u64 input_address = input ? virt_to_phys(input) : 0;
--
2.25.1
